Nearly Perfect Fluidity in the Dilute Fermi Gas: An Update

TL;DR

This paper reviews recent advances in understanding the transport properties of strongly correlated dilute Fermi gases, focusing on hydrodynamics, second order gradient terms, kinetic theory predictions, and experimental constraints on shear viscosity.

Contribution

It provides an updated analysis of the hydrodynamic behavior and transport coefficients of dilute Fermi gases, including new results on second order gradient terms and experimental tests of kinetic theory.

Findings

Current constraints on shear viscosity to entropy density ratio $/s$

Predictions of kinetic theory tested against experimental data

Structure of second order hydrodynamic terms elucidated

Abstract

In this contribution we summarize recent results on the transport properties of strongly correlated dilute Fermi gases. We discuss the hydrodynamic equations in the normal phase and present new results on the structure of second order terms in the gradient expansion. We also discuss predictions from kinetic theory, and show how these predictions can be tested using experimental data on elliptic flow. We summarize current constraints on the shear viscosity to entropy density ratio $\eta/s$.